Leaching and precipitating process and apparatus



NOV. 15, J. BU E T 2,136,372

LEACHING AND PRECIPITATING PROCESS AND APPARATUS Filed March 25, 1936 3Sheets-Sheet l 7&1.

AC FD STORAGE TANK LEAHING- TANK LEACHING: TANK Pnecmrnmu TANKPRECIPITATION TANK Acm REcEn/lNG TANK Invenlor 276/272 13 .Zurnef gum 5m5 I A llomeyJ' NOV. 15, 1-938. J BURNETT 2,136,372

LEACHING AND PREGIPII'ATING PROCESS AND APPARATUS Filed March 25, 1936 3Sheets-Sheet 2 ACID STORAGE LEAOHING- 37 TANK LEACHING TANKPRECIPITATION TANK ACID Rscswma 36 TA NK Invenlor pwm a A Home) Nov. 15,1938. J. L. BURNETT 2,

LEACHING AND PRECIPITATING PROCESS AND APPARATUS Filed March 25, 1936 3Sheets-Sheet 3 v Invenlor 175/112 .Z Burner! and a A llomcy;

Patented Nov; 15, 1938 LEACHING AND PRECIPITATING PROCESS AND APPARATUSJohn L. Burnett, St. Louis, Mo.

Application March 25, 1936, Serial No. 70,901

7 Claims.

My invention relates generally to means for obtaining precious andsemi-precious metals from,

their ores and particularly to a leaching and precipitating process andto apparatus for carrying 5 out the process, and an important object ofmy invention is to provide means of the character indicated whichgreatly reduces the time usually required for treating ores,particularly copper ores, and ensures a higher percentage of recovery,and obtaining the metal in a purer state.

Another important object of my invention is to provide process andapparatus of the character indicated above in which upward gravity flowof precipitating and leaching agent is advantageously arrangedcontinuously through the ore beds, the leaching agent rising to a fixedpoint so as to overflow. therefrom.

Another important object of my invention is to provide in method andapparatus as indicated above, means and operations procuring gravityupward flow of the leaching solution through false bottoms of stone of afiltering nature, and wherein. force pumping is done away with exceptfor returning the acid from the receiving tank to the acid storage tankto be rejuvenated or fortified to the required strength.

Another important object of my invention is to provide apparatus of thecharacter indicated which is simpler and lower in cost than other typesof apparatus now being used.

Another important object of my invention is to provide apparatusaifording a continuously operating system, and which is adapted withoutmajor changes to the leaching and precipitation of any ores which can betreated by presently known agents.

Other important objects of my invention willbe apparent from a readingof the following description of my method or process, in connection withthe drawings, wherein for purposes of illustration I have shown apreferred embodiment of the apparatus of the invention.

In the drawings:

Figure 1 is a general diagrammatic representation of apparatus inaccordance with the present invention, showing the tank and connectingview taken through the two precipitating tanks.

Referring in detail to the drawings, the numeral 5 generally designatesthe acid storage tank which is of suitable size and capacity and has apipe 6 leading from near its bottom in a downward direction to connectwith the lateral branches 1 and 8 which lead to the leaching tanks 9 andill, the branches 1 and 8 having control valves II and I2, respectively,therein.

The lateral branches 1 and 8 communicate with the interior of theleaching tanks 9 and H1 at a level below that of the porousstone falsebottoms l3 and M, respectively, which are arranged above the bottoms ofthe said leaching tanks. Cleanout manholes I5 and I6, respectively, areprovided in the sides of the leaching tanks to enable handling the orebeds resting on the false bottoms l3 and Id.

The stone used for the false bottoms l3 and I4 is a porous syntheticstone of filtering character, such as the Fiitros which is manufacturedby Filtros Incorporated of East Rochester, New York, under Patent Nos.1,117,601, 1,118,441 and 2,008,327 and composed principally of silicasand bonded together with an artificial silicate fusing at temperaturesabove 2000 Fahrenheit.

Below the branches 1 and 8 are valved drain pipes 11 and I8 which leadinto the drain discharge pipe l9 which empties into the solution tank20.

At the selected level above the false bottoms l3 and M, the leachingtanks have overflow pipes 2i and 22 both of which feed the valveddischarge pipe 23 which leads into the upper part of the solution tank20.

The lower part of the solution tank 20 has a pipe 24 leading therefromand communicating with the adjoining valved branch pipes 25 and 26 whichlead respectively into the upper part of the precipitation tanks 21 and28, which have false bottoms 29 and 30 of similar character andarrangement to the false bottoms I3 and H in the leaching tanks, as wellas ore handling manholes 3l and 32. The precipitation tanks have valvedbranch pipes 33 and 34 which lead from the lower part thereof below thefalse bottoms 29 and 30 and which empty into the discharge pipe 35 whichleads into the upper part of the acid receiving tank 36.

For purposes of leading back into the acid storage tank 5 the solutionwhich is regenerated in the acid receiving tank, and for nootherpurposes, there is provided the valved pipe 31 which tank 5, and inwhich is interposed a suitable force pump 38. It is to be understoodthat the effect of the pump goes no farther than simply supplying theacid storage tank with the proper solution which then enters theleaching tanks and moves upwardly through the ore charges 39 and 40,respectively, by gravity alone.

The respective sizes of the various tanks is made evident in Figure 2 ofthe drawings. The various tanks are of acid resisting material and thetanks are so placed that the flow of acid from one to the other of thetanks is by gravity, and the various pipes are of the required size oflead pipe controlled by suitable acid resisting valves.

The acid storage tank which is the source of acid supply for the entireapparatus, is placed in such a manner that it is at the highestelevation of any of the tanks of the apparatus, the regula tion of theacid flow therefrom being under the control of the valves II and [2.

The actual leaching of the metal from the ore being treated occurs ineach of the leaching tanks 9 and Ill. The false bottoms l3 and M thenature of which has already been described, are placed about 14 or 16inches above the true bottom of the tanks and cover the entire crosssectional area of the tanks. The false bottoms rest upon timber supports4|, 4| and 42, 42, respectively. A proper charge of ground ore is placedupon the false bottoms and spread to a uniform depth to expedite theprocess of extraction.

From the acid storage tank 5 the acid supply enters each of the leachingtanks at the bottom and below the false bottom thereof, and then passesupwardly through the porous false bottom and enters the ore charge atits base. by gravity. From this time forward the process of leaching themetal from its native rock is expedited materially compared to the timecustomarily required for this process, due to the fact that theintroduction of the acid at the base of the ore charge sets up agitationwhich quickly throws the entire charge into a fornent and permitscontact of the acid with the ore in considerably less time than isrequired under present practice. Percolating upwardly through the orecharge enables the acid to extract the metal from its native rock andthe metal enters into solution with the acid and passes through anoverflow pipe near the top of the tank and into the solution tank nextin the system.

The extraction is completed when the supply of acid shows nodiscoloration or stain, and the flow thereof is then shut off. The acidcontent of the tank is then drained through the proper drain pipe, whichis valve controlled, at the true bottom of the tank and discharged intothe solution tank 20. 1 The tailings are cleaned therefrom and a new orecharge is placed in the leaching tanks and the process of extraction isrepeated. Each of the leaching tanks 9 and I0 is connected with thesource of supply, and discharge by the drains through the medium ofindividual connections, thereby making it possible for each of theseleaching tanks to be operated as a separate unit without interferingwith the function of the other leaching tank or with the apparatus as awhole. The capacity of each of the leaching tanks is one half unit byvolume.

Regarding the solution tank 20, this is third in the series in point ofelevation and sequence of process, entrance thereto being by proper pipeconnections I9 and 23 near the top thereof, by reason of which the metalin solution is introduced therein. No processing of the metal occurs inthe solution tank 20, its sole function being to store the solution.Discharge of the solution therefrom is by means of proper pipeconnections 24 regulated by valves connecting with the precipitationtanks 21 and 28 which are next in the system. The capacity of thesolution tank 20 is one full unit by volume.

The precipitation tanks 21 and 28 of which there may be two or more arefourth in point of elevation and sequence of process. The precipitationof the metal from its state of solution in the 'acid occurs in each ofthe tanks 21 and 28. As already stated each is equipped with a Filtrosstone false bottom identical in size, location and arrangement with thefalse bottoms of the leaching tanks 9 and Ill.

The tanks 2'! and 28 have the described pipe connections regulated byappropriate valves, the intake from the solution tank 20 being at thetop of the precipitation tanks above the false bottoms, and thedischarges of the precipitation tanks being at the bottoms of the tankbelow the false bottoms, and the discharge being into the acid receivingtank 36 which is next lower in elevation in the system.

The acid receiving tank 36 is arranged to permit the same to fill withsolution flowing from the solution tank 20, such flow being shut offimmediately sufiicient solution has been received therein. The reagent,the properties of which cause" precipitation of the metals to the falsebottoms of the precipitation tanks is here added, and such precipitationis allowed to proceed until all of the metal has settled upon the falsebottoms, indication of which is lack of discoloration or stain in theacid. This action usually requires about forty minutes. Upon completionof the precipitation, the discharge valves at the bottom of theprecipitation tanks are opened and the clear acid is permitted topercolate downwardly through the false bottom into the acid receivingtank 36.

The precipitates are then cleaned out of the tanks and the processrepeated. Each of the precipitation tanks is connected by individualpipe connections with the solution tank 20 and by individual dischargepipes with the acid receiving tank 36, so that each of the precipitationtanks may be operated as a unit without interfering with the functioningof the other tank or tanks 21 or 28, or the apparatus as a whole. Theprecipitation tanks 21 and 28 are of approximately one-half unitcapacity.

The acid receiving tank 36 is the lowest in point of elevation andsequence ofoperations and receives all acids passing through the variousstages of the apparatus as set forth above. No processing takes place inthe tank 36. Its intake from the preceding tanks is at the top and itsacid discharge is at its bottom, whence the acid is pumped by a-suitableacid pump into the acid storage tank 5 as already indicated.

The above describes a complete cycle of operation of the apparatus andwhen this is completed the cycle is repeated, indefinitely. The additionof fresh acid may be required before repetition to ensure properstrength of the acid. The capacity of the acid receiving tank 36 is onefull unit by volume.

It will be evident from the foregoing description of the apparatus thatthe present invention contemplates gravitationally circulating properacid medium upwardly through false stone filter bottoms into the orecharge, so that the acid engages the ore charge at the base thereof andin circulating upwardly therethrough by gravity, causes fomenting of theore charge and quick leaching thereof; that the circulation of the acidis kept up until it runs clear, indicating completion of the leaching.The process further comprises discharging the used acid into a solutiontank from which it is led into the upper part of precipitation tanks inwhich the concentrates are held on false bottoms, and through which theacid circulates downwardly by gravity, so that the acid discharges intoan acid receiving tank. The process further comprises the operation oftreating the acid in the acid receiving tank with reagents andstrengtheners, and pumping the resultant into the acid storage tankwhich is in direct feeding relation by gravity to the leaching tanks.Although my process and apparatus, contemplates the use of any reagentsor acids or other materials now in use for the leaching andprecipitation of precious and semi-precious metals, I find that- Thefollowing acids and reagents, produce quicker and more completeextraction in the operation of my process and apparatus.

For extracting gold and silver precipitate the gold and silver.

Copper Sulphurous Bicarbonate. of soda being used to. precipitate thecopper.

Although I have shown and described herein preferred embodiments of theapparatus and of the process of my invention, it is to be definitelyunderstood that I do not desire to limit the application of theinvention specifically thereto, and any change or changes may in thestructure and arrangement of the parts, and in the sequence and durationof the steps and operations concerned in the process, within the spiritof the invention and the scope of the subjoined claims.

What is claimed is:-

1. Apparatus for obtaining metal from metal bearing ore, said apparatuscomprising a leaching tank, having a porous stone false'bottom 'on whichthe ore charge rests, an acid storage tank gravitationally feeding thelower part of said leaching tank below said false bottom, whereby theacid is caused to rise through the ore charge, overflow means at theupper part of the leaching tank for leading off-the metal bearing acid,a solutifii tank into which said overflow means empties, a precipitationtank havinga porous stone false bottom above which said 'overflow meansenters, an acid receiving tank, acid drain means leading from theprecipitating tank below its false bottom into the upper part of saidacid receiving tank, conduit means leading from the lower part of saidacid ,receivin'g tank to the upper part of said acid storage tank, andforce pump means interposed in said conduit means for moving the acidtherein.

2. Apparatus for obtaining metal from metal bearing ore, said apparatuscomprising a leaching tank having a porous stone false bottom on whichthe ore charge rests, an acid storage tank gravi-' tationallyfeeding thelower part of said leaching tank below said falsebottom, whereby theoverflow means at the upper part of the leaching tank for leading. offthe metal bearing acid, a solution tank into which said overflow meansempties, a precipitation tank having'a porous stone false bottom abovewhich said overflow means enters, an acid receiving tank, acid drainmeans leading from the precipitating tank below,

its false bottom into the upper part of said acid receiving tank,conduit means leading from the lower part of said acid receiving tank tothe Y gravitational flow of acid through the apparatus. 3. Apparatus forobtaining metal from metal.

bearing ore, said apparatus comprising a leaching tank having a porousstone false bottom: on

which the ore charge rests, an acid storage tank gravitationally feedingthe lower part ofs-said leaching tank below said false bottom, wherebythe acid is caused to rise through the ore charge,

overflow means at the upper part of the leaching tank for leaching offthe metal bearing acid, a solution tank into which said overflow meansempties, a precipitation tank having a porous stone false bottom abovewhich said overflow means enters, an acid receiving tank, acid drainmeans leading from the precipitating tank below its false bottom intothe upper part of said acid receiving tank, conduit means leading fromthe lower part of said acid receiving tank to the upper part of saidacid storage tank, and force pump means interposed in said conduit meansfor moving the acid therein, said leaching tank and said precipitationtank having respective manholes enabling removal of matter from the topof their respective false bottoms.

4. Apparatus forobtaining metal from metal bearing ore, said apparatuscomprising a leaching tank having a porous stone false bottom on whichthe ore charge rests, an acid storage tank gravitationally feeding thelower part of said leaching tank below said false botttom, whereby theacid is caused to rise through the ore charge, overflow means at theupper part of the leaching tank for leading off the metal bearing acid,a solution tank into which said overflow means empties, a precipitationtank having a porous stone false bottom above which said overflow meansenters, an acid receiving tank, acid drain means leading from theprecipitating tank below its false bottom into the upper part of saidacid receiving tank, conduit means leading from the part of said acidreceiving tank to the upper part of said acid storage tank, and forcepump means interposed in said conduit means for moving the acid therein,said leaching tank comprising at least two distinct compartments, andvalve controlled means extending between the compartments and the acidstorage tank and the solution tank enabling individual or concertedoperation of said compartments.

5. Apparatus for obtaining metal from metal bearing ore, said apparatuscomprising aleaching tank having a porous stone false bottom on whichthe ore charge rests, an acid storage tank gravitationally feeding thelower part of said leaching tank below said false bottom, whereby theacid is caused to rise through the ore charge, overflow means at theupperpart of the leaching tank for leaching off the metal bearing acid,a solua precipitation tank having a porous stone false bottom abovewhich said overflow means enters, an acid receiving tank, acid drainmeans leading from the precipitating tank below. its false bottom intothe'upper part of said acid receiving tank, conduit means leading fromthe lower part of said acid receiving tank to the upper part of saidacid storage tank, and force pump means interposed in said conduit meansfor moving the acid therein, said precipitation tank comprising at leasttwo distinct compartments, and second valve controlled means extendingbetween said solution tank and said compartments and between saidcompartments and said acid receiving tank enabling independent orconcerted operation of the compartments.

6. A method of obtaining metal from metal bearing ore, said methodcomprising confining a quantity of the ground ore on top of a porousstone false bottom, then gravitationally circulating acid upwardlythrough said false bottom in a manner to contact the base of the ore andpercolate the acid upwardly therein so as to produce fomenting of theore, and thereby rapid leaching thereof, then permitting the upwardlypercolated metal bearing acid to overflow, then confining the overflowedmetal bearing acid above 7 2,186,372 tion tank into which said overflowmeans empties,

a porous stone false bottom and precipitating the metal, then permittingthe acid to filter through the false bottom and leave the metal on thefalse bottom, then gravitationally conveying the flltered acid to anacid regenerating member for restoring the same.

7. A method of obtaining metal from metal bearing ore, said methodcomprising confining a quantity of the ground ore on top of a porousstone false bottom, then gravitationally circulating acid upwardlythrough said false bottom in a manner to contact the base of the ore andpercolate the acid upwardly therein so as to produce fomenting of theore, and thereby rapid leaching thereof, then permitting the upwardlypercolated metal bearing acid to overflow, then confining the overflowedmetal bearing acid above a porous stone false bottom and precipitatingthe metal, then permitting the acid to filter through the false bottomand leave the metal on the false bottom, then gravitationally conveyingthe filtered acid to an acid regenerating member for restoring the same,then force pumping the restored acid from said rejuvenating member to apoint elevated above the originally confined ore to enablegravitationally circulating the acid upwardly through the ore' charge.

JOHN L. BURNE'I'I.

